Help in Moving Average Query

Question

Hello,
I would like to have a query for finding moving average. based on some conditions.
I have written query as follows:
SELECT Column1,
MONTH_END_DATE,
(AVG(sum(Col2 *(case when (Col3 ='XYZ') then 1 else 0 end)))OVER (PARTITION BY Column1 ORDER BY MONTH_END_DATE ROWS 5 PRECEDING)) AS AVG_XYZ,
sum(Col2 *(case when (Col3 ='XYZ') then 1 else 0 end)) as Cumm_XYZ
FROM
Table_cd
WHERE
Column1 ='1234567'
GROUP BY Column1, MONTH_END_DATE.
My problem is if there are no data in a month, then the average calculated will vary from the required.
For Eg., If i have to find the average of months between JULY and DECEMBER and if the table doesnt have data in the month of OCTOBER, NOVEMBER then while finding the average it will consider only 4 Months instead of 6 Months..So is it possible to write query such that if there are no data in a month then consider the values for that month as zero and then find the average..
If anybody can help me in this regard, it will be very useful

Answer 1

Mr.BluShadow if u can just show me how i can find
average for the values returned by the example
written by you, it would be very helpful..Obviously the hint wasn't enough... here's another...
SQL> ed
Wrote file afiedt.buf
  1  with t as (select to_date('01/07/2007','DD/MM/YYYY') as dt, 1 as val from dual union all
  2             select to_date('02/07/2007','DD/MM/YYYY'), 2 from dual union all
  3             select to_date('03/07/2007','DD/MM/YYYY'), 3 from dual union all
  4             select to_date('04/07/2007','DD/MM/YYYY'), 4 from dual union all
  5             select to_date('01/08/2007','DD/MM/YYYY'), 5 from dual union all
  6             select to_date('02/08/2007','DD/MM/YYYY'), 6 from dual union all
  7             select to_date('03/08/2007','DD/MM/YYYY'), 7 from dual union all
  8             select to_date('01/09/2007','DD/MM/YYYY'), 8 from dual union all
  9             select to_date('02/09/2007','DD/MM/YYYY'), 9 from dual union all
10             select to_date('03/09/2007','DD/MM/YYYY'), 10 from dual union all
11             select to_date('01/12/2007','DD/MM/YYYY'), 11 from dual union all
12             select to_date('02/12/2007','DD/MM/YYYY'), 12 from dual union all
13             select to_date('03/12/2007','DD/MM/YYYY'), 13 from dual union all
14             select to_date('04/12/2007','DD/MM/YYYY'), 14 from dual
15            )
16  --
17  select m.dt, AVG(NVL(t.val,0)) as val
18  from t, (select add_months(to_date('01/07/2007', 'DD/MM/YYYY'),rownum-1) as dt from dual connect by rownum <= 6) m
19  where m.dt = trunc(t.dt(+),'MM')
20  group by m.dt
21* order by dt
SQL> /
DT               VAL
01-JUL-07        2.5
01-AUG-07          6
01-SEP-07          9
01-OCT-07          0
01-NOV-07          0
01-DEC-07       12.5
6 rows selected.
SQL>